The present invention relates to novel organosilicone polymers and their use in the manufacture of urethane cellular products, particularly flexible polyether polyol-based urethane foams.
It is well known that the urethane linkages of urethane foams are formed by the exothermic reaction of a polyfunctional isocyanate and a polyfunctional active hydrogen-containing compound in the presence of a catalyst, and that the cellular structure of the foam is provided by gas evolution and expansion during the urethane-forming reaction. In accordance with the "one-shot process" which is the most widely used industrial technique, direct reaction is effected between all of the raw materials which include the polyisocyanate, the active hydrogen-containing compound, the catalyst system, blowing agent and surfactant. A major function of the surfactant is to stabilize the urethane foam, that is, prevent collapse of the foam until the foamed product has developed sufficient gel strength to become self-supporting.
Although certain techniques of urethane manufacutre such as the "one-shot process" and certain components of the foam formulation such as the polyisocyanates, amine catalyst and blowing agent, are generally useful, a specific problem associated with the production of a particular type of urethane foam and the solution thereto are often peculiar to the chemical and physical structure of the desired foamed product. In particular, the efficacy of the foam stabilizer is usually selective with respect to the formation of a particular type of foam. One factor to be considered in the evaluation of stabilizing efficacy is surfactant potency which is reflected by two types of measurements. One is the measured original height to which the foam rises as it is being formed. From this standpoint, the greater the foam rise, the more potent is the surfactant. The second potency measurement is concerned with the ability of the surfactant to maintain the original height of the foam once it has formed. Foams produced with surfactants which have good potency in this second request undergo a minimum of settling or "top collapse" which may otherwise contribute to split formation and other foam defects.
It is also desirable that the foam stabilizer have good processing latitude, that is, ability to provide foams of satisfactory quality over a relatively wide range of operating variables such as, for example, concentration of surfactant and metal co-catalysts which are normally employed in the manufacture of flexible polyether-based foams. The more common co-catalysts are organic derivatives of tin and thus sensitivity to variation in co-catalyst concentration is more particularly referred to in the art as "tin operating latitude." Decreasing the concentration of such co-catalysts below normal levels is sometimes necessary to improve breathability of the foam but, if the effectiveness of the foam stabilizer is narrowly dependent on co-catalyst concentration (that is, its tin operating latitude is poor), the desired enhanced breathability may be offset by foam weakness due to split formation.
The search for improved surfactants for stabilization of polyurethane foams is further complicated by the tendency of such foams to ignite readily and burn and the need to reduce their flammability This characteristic is particularly objectionable in the case of flexible polyurethane foams in view of the use of such foams in many applications where fire is especially hazardous such as their use in automotive seat cushions and household furniture cushioning. One approach to reducing flammability of flexible foams is to include a flame-retarding agent such as various phosphorus and/or halogen-containing compounds as a component of the foam-producing reaction mixture. It is found, however, that surfactants which may otherwise be effective stabilizers of non flame-retarded foams, may be deficient as stabilizers of foams containing a flame retardant. It is also desirable that the siloxane surfactant possess a good combination of potency and processing latitude in the stabilization of flexible polyether urethane foams. Thus, there is still room in the art for improved organosilicone foam stabilizers.
Accordingly, it is an object of this invention to provide new and useful organosilicone polymers which have particular application in the manufacture of flexible polyether polyol-based polyurethane foams. It is another object of this invention to provide a novel process for producing flexible polyether polyurethane foam using said organosilicone polymers as the foam stabilizer. A further object is to provide flexible polyether polyurethane foams produced by said porcess. Various other objects and advantages of this invention will become readily apparent from the following description and appended claims.